Heating furnace



Nov. 10, 1964 R- A. HOGUE 3,156,453

HEATING FURNACE Filed March 20. 1961 INVENTOR.

United States Patent 0 3,156,453 HEATING FURNACE Robert A. Hogue, Gary, Ind., assignor to Inland Steel Company, Chicago, Ill., a corporation of Delaware Filed Mar. 20, 1961, Ser. No. 96,785 3 Claims. (Cl. 263-6) The invention relates to an improved heating furnace.

The heating furnace to which the improvement relates is of a type used in the steel industry in heating slabs, blooms or billets or the like, which are referred to herein generically as billets. One of the problems encountered is that cold spots or skid marks result when the billets me heated in a furnace having cooled skids. The skid marks are caused when the billets contact the water cooled skids which support the billets as they travel through the furnace. These skid marks impair the quality of the billet, typically steel, in that the billet lacks uniform metallurgical properties, and the gauge of the billet is affected. Hence, it can be seen that the furnace does not properly perform its function of raising the billet to a uniform temperature Within a short time. By employment of the invention, in addition to the above advantages, the furnace productivity is increased due to the fact that a shorter heating time is required to give the billet its required uniform temperature.

The invention comprises the addition of passages in the hearth disposed vertically below the skid marks on the billet. Heaters are used to raise the temperature of the air and other gases in the passages so that the local portion of the billets having the skid marks receive a quantity of heat not available to the other portions of the billet. The use of a heater in the form of oil burners for raising the temperature of the air and other gases in the passages is desirable since the temperature can be raised quickly and depending upon the amount of oil admitted to the oil burner the temperature can be controlled. The exhausted air and other gases from the oil burner are useful in heating the billet in other portions of the furnace.

Other advantages will be readily apparent when reference is made to the drawing and the remainder of the specification.

The drawing is a perspective view of the furnace which embodies the invention, the figure being partly in crosssectional form.

The furnace which embodies the invention is designated generally at 10. It is a typical heating furnace used in the steel industry for heating billets, the general construction of which is shown and described on page 408 of The Making, Shaping and Treating of Steels, seventh edition, published by the United States Steel Corporation. A plurality of cooled skids 11 support the billet in its travel through the furnace. The skids 11, being hollow and adapted to receive a suitable coolant, form part of a cooling circuit. A plurality of conduits 12 of the cooling circuit, only one of which is shown in the drawing, supply the coolant, preferably water, to their respective skids. Suitable means, not shown, are provided for pumping the coolant through the circuit. The billet is transferred from the skids to a hearth 13 which is used to support the billet in what may be called the soaking zone. A plurality of passages 14 are disposed in the hearth vertically below and parallel to the center line of each of the skids 11. The passages are preferably defined by a tubing 21 which is composed of a material which can withstand high temperatures. The tubing can be cast into the hearth which is composed of a refractory material. A plurality of heaters in the form of oil burners 15 are provided for raising the temperature of the air in the passages. Of course, it is understood that there exist exhaust gases in the passages 14 which result when the oil burners are operated. Passages 14 are arranged to constitute a part of a heating means since combustion can take place therein when the respective oil burners are operated. Each passage has an outlet 16 which permits the exhausting of the unused heat generated by the heating means. The exhaust gases are used, if desired, to heat the billet before it has reached the soaking zone.

Each oil burner 15 is of well known form and is provided with an air inlet 17 and an oil inlet 18. Suitable conventional igniting means, not shown, are used to start the flame in the oil burner. Heater 19 is used to heat the billet while it is supported on skids 11 in a heating zone 22, and a similar heater 20 is used to heat the billet while it is supported on the hearth 13 in the soaking zone. The billet M is shown leaving the furnace on its way to other portions of the steel mill.

The above-described embodiment being exemplary only, it will be understood that the present invention comprehends organizations differing in form or detail from the presently described embodiment. Accordingly, the invention is not to be considered as limited save as is consonant with the scope of the following claims.

What is claimed is:

1. In a billet heating furnace the combination comprising a plurality of skids located in the heating section of the furnace for supporting the billets as they travel through the furnace, means for cooling each skid indeendently of each other, a substantially planar soaking hearth member positioned in a soaking section of the furnace adjacent to the skids along which billets are adapted to be moved while supported thereby in the furnace, a plurality of enclosed heating passages extending below the planar surface of said hearth with each said passage disposed vertically below the hearth surface and in alignment with the axis of one of the said skids, an individual heating means for producing combustion within the confines of each heating passage beneath the hearth, and means to direct exhaust gases from said heating passages into the furnace in the region of the skids.

2. In a heating furnace the combination of a plurality of skids for passing billets from a heating section of the furnace to a soaking chamber, an internal cooling means within each skid, each skid being supported and disposed in the furnace heating zone for supporting a billet as it travels through the furnace, a hearth member located in the soaking section of the furnace for receiving each billet as it travels through the furnace from the skids, a plurality of closed internal passages of a number corresponding to the number of skids disposed within the hearth vertically below the billet receiving surface and in alignment with the center line of the skids and terminating substantially at the heating zone within the furnace, a separate heater means for producing combustion within the confines of each of the internal passages beneath the hearth surface, the terminating opening of the passages into the furnace heating zone providing an outlet whereby residual heat developed within the separate passages is directed into the heating area in the region of the skids.

3. In a heating furnace, the combination of a plurality of billet-carrying skids disposed in the heating zone and adapted for supporting billets as they travel through the furnace, a cooling means associated with and located beneath each skid for cooling the billets in the skid-supported regions, means for supplying heat to the billets in the heating zone within which the skids are located, a substantially planar hearth member located at the terminating ends of each of the skids for receiving billets from the skids and supporting the billets in a soaking region of the furnace when passed thereto from the skids, a plurality of enclosed heating passages located beneath the supporting area of the substantially planar hearth and in align- 3 4- ment with the center lines of the several skids, each en- References Cited in the file of this patent closed passage terminating at and opening into substan- A tially the region of termination of the skids, a heater UNITED STATES PATENTS means for each enclosed passage for producing combus- 1,912,933 Culbertson June 6, 1933 tion interiorly of the confines of each of said passage, the 5 2,180,089 McDelmott 19 9 terminating ends of each enclosed passage opening into 2,776,128 Ncs itt et a1 Jan. 1, 1957 the furnace heating zone and providing an outlet means 2,892,224 Bauer June 30, 1959 whereby the heat of the passages is supplied as residual 3,081,073 Conway Mar. 12, 1963 heat in the combustion region of the furnace. 

1. IN A BILLET HEATING FURNACE THE COMBINATION COMPRISING A PLURALITY OF SKIDS LOCATED IN THE HEATING SECTION OF THE FURNACE FOR SUPPORTING THE BILLETS AS THEY TRAVEL THROUGH THE FURNACE, MEANS FOR COOLING EACH SKID INDEPENDENTLY OF EACH OTHER, A SUBSTANTIALLY PLANAR SOAKING HEARTH MEMBER POSITIONED IN A SOAKING SECTION OF THE FURNACE ADJACENT TO THE SKIDS ALONG WHICH BILLETS ARE ADAPTED TO BE MOVED WHILE SUPPORTED THEREBY IN THE FURNACE, A PLURALITY OF ENCLOSED HEATING PASSAGES EXTENDING BELOW THE PLANAR SURFACE OF SAID HEARTH WITH EACH SAID PASSAGE DISPOSED VERTICALLY BELOW THE HEARTH SURFACE AND IN ALIGNMENT WITH THE AXIS OF ONE OF THE SAID SKIDS, AN INDIVIDUAL HEATING MEANS FOR PRODUCING COMBUSTION WITHIN THE CON- 